Did u plug the USB into the GPS and let it charge over night?? if not try that and see if the error goes away.

question : is the battery really a battery or merely a capacitor?
I'm asking this question because it doesn't seem to hold the charge very well causing all sorts of errors.
How could we do to fix this problem, my GPS is very unreliable, "no GPS communication" error is happening randomly and so is GPS booting or not at startup.

This is quite annoying and spoiling the joy, all is otherwise working reasonably well with defaults settings or close.

Bob, your is using 5S so the config is maintained by the battery. and yes, it is battery. 3V rechargeable lithium button cell

and you should ready i2c okay with running number and SPI Okay with running number.

also flash all the corresponding firmware to NC/FC.

For GPS, please follow my earlier load on setup.

thanks Dan
- all MK hardware is flashed with latest FW
- Ublox GPS hasn't been re-flashed yet, does it need to, if yes, which FW?
- when it comes to Ublox config file, you said I should use the one G posted a few threads back, is this correct for the LEA5S ?

I just received some replacement NC-MK3Mag-GPS free of charge from MaximusRC (thanks Max, you're a great guy!)

This is an older different type, but very nicely made.
Do you guys (Dan, G?) have info on how to connect NC to FC and other possible connections (there is only 3 pins used for SPI, the other newer NC have 2x 3 pins)?
What FW can/should I use to flash these?

Thanks for the great help to all the contributors, this is moving fast!
Bob

question : is the battery really a battery or merely a capacitor?
I'm asking this question because it doesn't seem to hold the charge very well causing all sorts of errors.
How could we do to fix this problem, my GPS is very unreliable, "no GPS communication" error is happening randomly and so is GPS booting or not at startup.

This is quite annoying and spoiling the joy, all is otherwise working reasonably well with defaults settings or close.